This invention relates generally to sanitary valves and particularly to precision flow control valves adapted for use with fluids that are extremely sensitive to environmental exposure.
The advances of technology, especially in the area of the biological sciences such as those concerned with producing genetically altered bacteria and the like, has given rise to a need for valves that are capable of precision flow control under highly sterile conditions. In addition, the valves must be rugged, reliable, minimize the possibility of build-up of flow deposits therein and permit thorough cleaning without dismantling. Such stringent requirements gave rise to the valve constructions of the invention.
The requirements of cleanability and minimum build-up of deposits are satisfied by the straight-through cylindrical valve chamber. The valve element, which is cylindrical and has a hemispherical tip, is supported in a cylindrical supporting means that intersects the valve chamber in a right angle. This permits a continuous seal to be maintained between the valve element and its support at all times, even during cleaning. This continuous seal condition obtains both the rotary configuration and the slidable configuration of the valve of the invention. The flanges that terminate the cylindrical valve chamber permit intimate mating with a pipeline and avoid non-smooth threaded surfaces, contributing to valve flow characteristics and minimizing the build-up of deposits.
U.S. Pat. No. 2,420,849, issued May 20, 1947, describes a valve that is transversely actuated and includes a generally T-shaped resilient sealing element for closing off the walls of the valve chamber when the barrier (valve plug) is moved to its closed position. That construction is not a straight-through valve chamber design, has threaded port openings and has a split valve body in which the seal between the valve plug and the valve chamber is broken during actuation of the valve.
U.S. Pat. No. 3,536,296, issued Oct. 27, 1970, discloses a precision flow valve that includes a spherical plug element with a tapered groove extending substantially completely around the ball. The valve chamber is not a straight-through design and presents many obstructions that would pose significant problems in cleaning.
The valve construction of the invention permits the pipeline to be drained completely for in-place sterilization. It is also simple in construction, easy to operate, and lends itself to either rotary or sliding actuation.